10 What is the energy source that moves the plates???Convection Currents- heated material expands (becomes less dense) and is forced up by heavier (more dense) material.“Blanket Effect” – Super continent, Pangea, insulated hot interior, causing heat build up and convection currents.Plates are drug along by this movement

31 Volcanic Islands are found only at ACTIVE plate boundariesForms LITHOGENIC SEDIMENT- break up of rocks (Quartz)Andros no Quartz –no volcanoBiogenic sedimentMade of skeletons and shells of marine organisms

33 Active Plate Margin vs Passive Plate MarginActive Margin- little or no shelf (shelf is crushed by movement)therefore minimal amount of fishing (no shallow water for plants), EXEPT at upwellingsPassive plate margin- very wide shelfTherefore (shallow water for plants) major fishing, because of shallow water

34 Shelf is only 8% of the ocean’s surface, but the most valuable.Average width 40 milesAverage depth 197 feetSlope is undetectable to eye (flat because turbidity (Mud) currents from rivers level out the slopeBiologically riches part of the ocean

41 Environment of Deep OceanHigh water pressure??Organisms are primarily H2O, because water is not compressible like airFood ??No light – no plants ??Most of food falls from the surfaceOxygen ??No light – no plants ??O2 is brought down by cold water density currents